Chair back



FIG. 1 is a perspective view of a chair back of the present invention;

FIG. 2 is a front elevation view of a chair back of the present invention;

FIG. 3 is a rear elevation view of a chair back of the present invention;

FIG. 4 is a right side elevation view of a chair back of the present invention, the left side elevation view being a mirror image thereof;

FIG. 5 is a top plan view of a chair back of the present invention; and,

FIG. 6 is a bottom plan view of a chair back of the present invention.

The features of the chair back shown in broken lines are for illustrative purposes only and form no part of the claimed design. 

I claim the ornamental design for a chair back, as shown and described. 